Coupling means for connecting molten metal transporting lines

ABSTRACT

Coupling means particularly useful in a metal diecasting apparatus for connecting the metal-conducting passageway in the pumping and metering assembly to the metal-conducting passageway in the delivery line. The male half of the coupling comprises a stud fitting having a ball-shaped head portion and a lengthwise axial bore in communication with the outlet end of the pumping and metering assembly passageway. A female half of the coupling is defined by a bell-shaped fitting having a central lengthwise bore in communication with the inlet end of the delivery line passageway. A lower portion of the bore defines a frustoconical cavity having tapered sidewalls adapted to wedgingly engage the ball-shaped head portion of the stud fitting to provide an essentially liquidtight joint.

United States Patent [72] lnventor Gilbert C. Jackson Midland, Mich. [2|] App]. No, 838.285 [22] Filed July 1, 1969 [45] Patented June 1, 1971 [73] Assignee The Dow Chemical Company Midland, Mich.

[541 COUPLING MEANS FOR CONNECTING MOLTEN METAL TRANSPORTING LINES 5 Claims, 2 Drawing Figs.

52 us. Cl 137/563, 251/144, 251/319, 222/385 [51] Int. Cl F16k 1/00 [50] Field of Search 137/565,

[56] References Cited UNITED STATES PATENTS 1,484,512 2/1924 Lightfoot 285/9X 2,040,008 5/1936 Kreidel..... 285/261X 2,774,618 12/1956 Alderson 285/261X 3,115,352 12/1963 Heerlein 285/9 3,233,549 2/1966 Howe 285/9X 3.323.651 6/1967 Hauxwell et al. 285/9X FOREIGN PATENTS 922,562 12/1954 Germany 285/261 Primary Examiner-M. Cary Nelson Assistant Examiner-R. B. Rothman Atlorneys-Griswold & Burdick, V. Dean Clausen and William R. Norris ABSTRACT: Coupling means particularly useful in a metal diecasting apparatus for connecting the metal-conducting passageway in the pumping and metering assembly to the metal-conducting passageway in the delivery line. The male half of the coupling comprises a stud fitting having a ballshaped head portion and a lengthwise axial bore in communication with the outlet end of the pumping and metering assembly passageway. A female half of the coupling is defined by a bell-shaped fitting having a central lengthwise bore in communication with the inlet end of the delivery line passageway. A lower portion of the bore defines a frustoconical cavity having tapered sidewalls adapted to wedgingly engage the ball-shaped head portion of the stud fitting to provide an essentially liquidtight joint.

PATENTEBJUH nan 358L767 INVENTOR. 6 /'/b ervC. J0 ckson COUPLING MEANS FOR CONNECTING MOLTEN METAL TRANSPORTING LINES BACKGROUND OF THE INVENTION The invention relates broadly to handling of molten metal. More specifically, the invention is directed to an improved coupling means for transferring molten metal from a pumping and metering assembly to a delivery line in a diecasting apparatus.

In a typical diecasting apparatus the molten metal to be diecast is contained in a suitable vessel, such as a crucible or melting pot. The molten metal is transferred to a diecasting machine through a pumping and metering assembly and a delivery line or transfer pipe coupled to the assembly. Molten metal is drawn into a pump intake chamber which houses the impeller unit of a centrifugal pump. The impeller unit drives the metal through a passageway containing a metering valve. The valve meters a predetermined quantity of the metal, which passes through the coupling and directly into a passageway in the delivery line. From the delivery line the metal is ejected through a nozzle portion at the outlet end of the line and into the shotwell of a diecasting machine.

One of the more common diecasting metals is a magnesiumbased alloy which, in a molten state, is readily oxidizable by atmospheric oxygen. It is essential therefore in die-casting magnesium-based metals, to maintain the delivery line substantially completely full of the liquid metal during the casting operation. Any interruption of metal flow into the delivery line will produce open spaces in the metal stream in the delivery line passageway, which cause suction of air into the passageway through the nozzle portion. This resulting in surface oxidation of the metal remaining in the delivery line passageway and creates oxide "slugs" which plug the passageway in a relatively short time.

In the presently available die-casting apparatus a principal cause of interrupted metal flow in the delivery line is the coupling means which joins the pumping and metering assembly to the delivery line. In a common type of coupling used for this purpose the male half of the coupling is a fitting having a central bore therethrough and a head portion with generally tapered sidewalls. The male fitting is mounted on the pumping and metering assembly at the outlet end of the metal-conducting passageway in the assembly. The female half of the coupling is a generally bell-shaped fitting having a central frustoconical bore section, the fitting being mounted integral with the inlet end of the metal-conducting passageway in the delivery line. In coupling the delivery line to the pumping and metering assembly, the frustoconical bore section of the female fitting fits over and wedgingly engages the tapered sidewalls of the head portion of the male fitting.

The prior coupling means has been generally unsatisfactory with regard to maintaining the passageway in the delivery line full of metal during the casting operation. For example, the delivery line, which usually comprises several feet of an insulation-covered pipe, exerts a substantial downward pull at the nozzle or discharge end of the pipe, due to the weight of the line. The downward pull of the line thus has a tendency to tip or cant the female fitting at the inlet end of the line such that the conical bore section of the fitting gets out of alignment with the tapered head portion of the male fitting. When the female fitting is canted in this manner the coupling seal" is broken and the liquid metal in the delivery line will leak between the coupling fittings and back into the melting pot. The usual procedure, in attempting to prevent the coupling from leaking, is to hammer the female fitting down into the male fitting. Forcing the coupling fittings together in this manner exerts considerable strain on the pumping and metering assembly housing and frequently results in cracking the housing. A further disadvantage of the prior coupling is that it is not flexible enough to permit up and down adjustment ofthe nozzle end of the ,delivery line without breaking the coupling "seal. This is particularly undesirable in that it is frequently necessary to vary the distance of the delivery line nozzle from the shotwell in order to deliver metal into the shotwell under optimum conditions for producing castings.

Other means for coupling the pumping and metering assembly to the delivery line have included use of railroad unions or a coupling similar to that described above, but with a ring-seal fitted into the .bore section of the female fitting. Railroad unions have the general disadvantage of being difficult to disconnect, particularly under the surface of a molten metalbath. Additionally, the unions are not flexible enough to allow for nozzle adjustment of the delivery line. The ring-seal type of coupling has the same general drawbacks as the firstmentioned coupling means described above, since the structure ofboth couplings is essentially the same.

SUMMARY OF THE INVENTION A broad object of the invention is a coupling means which provides an essentially liquidtight connection between lines for transporting molten metal.

A more specific object is to provide a coupling for joining the pumping and metering assembly to the delivery line in a metal diecasting apparatus which provides a better liquid metal seal" than the prior couplings.

Another object is to provide a coupling of the character described which permits more flexibility in adjusting the delivery line ofa diecasting apparatus.

Still another object is to provide a coupling as described which permits the delivery line in the diecasting apparatus to be easily and readily disconnected from the pumping and metering assembly to facilitate cleaning of the delivery line.

Broadly stated, the invention provides an improved coupling means for effecting transfer of molten metal from a pumping and metering assembly to a delivery line. A male half of the coupling defines a stud fitting having a ball-shaped head portion and a lengthwise axial bore extending therethrough. I

The stud fitting is upstandingly affixed to the pumping and metering assembly, such that the lower end ofthe fitting bore is in direct communication with the outlet end of metal conducting passageway in the assembly. The opposite or female half of the coupling defines a generally bell-shaped fitting with a central bore extending generally lengthwise through the fitting. The bore in the female fitting includes a lower bore section adapted to sealingly engage the head portion of the stud fitting. An upper bore section obliquely intersects the lower bore section and is directly joined to the inlet end of a metalconducting passageway in the delivery line. In a preferred application the coupling means of this invention is employed in a metal diecasting apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation view, partly schematic and partly in section, of a conventional diecasting apparatus which includes the coupling means of this invention.

FIG. 2 is an enlarged detailed view, mostly in section, of the coupling means illustrated in FIG. I.

The drawing illustrates only one of numerous embodiments within the scope of the invention, the form shown being selected for convenient illustration and clear demonstration of the principles involved.

DESCRIPTION OF A PREFERRED EMBODIMENT In the drawing, referring particularly to FIG. 1, there is illustrated a portion of a conventional diecasting apparatus of the type employed in diecasting ofa magnesium-based alloy. The diecasting apparatus 10 includes a crucible or melting pot 12 for containing the molten metal 14 to be die-cast. A pumping and metering assembly, as generally designated by numeral 16, provides means for transferring the molten metal 14 from the crucible 12 to a delivery line 18. From delivery line 18 the metal is injected into the shotwell 20 of adiecasting machine (not shown). Pumping and metering assembly 16 comprises basically a centrifugal pump unit 22 and a metering valve unit 24. The lower portion of assembly 16, which is suspended in the metal melt 14, includes a metal-conducting passageway 26. The metal inlet end of passageway 26 is defined by a chamber which houses an impeller unit 2211 of the pump 22. A piston-type metering valve 24a is positioned in passageway 26 downstream from the impeller unit 22a. Valve 24a is operated by a suitable electrical control (not shown) to meter a predetermined amount ofthe metal 14 through passageway 26 into the delivery line 18. As indicated by the flow direction arrows in FIGS. 1 and 2, the metal 14 is transferred from the pumping and metering assembly 16 into the delivery line 18 through a coupling means 28, which connects the passageway 26 in assembly 16 with a metal-conducting passageway 30 in delivery line 18.

Coupling means 28 is more specifically illustrated in the enlarged detail view of HO. 2. As shown in H0. 2, the male half of coupling 28 comprises a stud fitting 32 having a ball-shaped head portion 320 and an axial bore 32b, which extends lengthwise through the fitting. Stud fitting 32 is upstandingly affixed to the pumping and metering assembly 16 such that the lower end of bore 32b is directly joined to the outlet end of passageway 26 in assembly 16. An upper or female half of coupling 28 defines a generally bell-shaped fitting 34 with a central bore extending substantially lengthwise through the fitting. The bore in fitting 34 comprises a lower bore section 350 and an upper bore section 36. Lower bore section 35a defines a frustoconical cavity having tapered sidewalls 35c, which are adapted to wedgingly engage the perimeter of'the ball-shaped head portion 32a of stud fitting 32. The lower end of upper bore section 36 communicates with the lower bore section 35a by forming an oblique intersection with a transverse upper wall 35d of the lower bore section. Preferably, the bore section 36 intersects bore section 351': at an angle of about 45 such that the bore section 36 will extend generally diagonally through the upper part of fitting 34. The metal conducting passageway 30 of delivery line 18 fits into the upper portion of upper bore section 36 and the outer wall of the passageway is secured to the fitting 34 to thereby directly join bore section 36 with the (metal) inlet end of passageway 30.

As will be apparent from the foregoing description and the accompanying drawing, the coupling means 28 provides an excellent connection for the transfer of the molten metal 14 from the pumping and metering assembly 16 to the delivery line 18. Referring to FIG. 2, it will be seen that the tapered sidewalls 35: of bore section 350 provide a substantially snug wedging-type fit of fitting 34 on the perimeter of the ballshaped head portion 32a of stud fitting 32. The snug fit thus obtained provides a good liquidtight seal" which prevents the molten metal 14 in passageway 30 of delivery line 18 from leaking between the coupling fittings and back into the crucible 12. Another advantage of the coupling 28 is the swiveltype" joint it provides, which permits substantially unlimited flexibility of delivery line 18, as regards either up or down or lateral adjustment of the delivery line. The coupling has another particularly desireable feature which is not found in the prior coupling means. With a swivel-type joint the coupling may be readily disconnected when it is desired to remove plugging solids from the passageway 30 in delivery line 18.

ln the preferred embodiment illustrated in FIGS. 1 and 2, coupling 28 includes a holddown means 37 for urging the bellshaped fitting 34 downwardly against stud fitting 32. Holddown means 37 is defined generally by an upstanding bar or rod 37a. The lower end of rod 370 has a recess therein adapted to engage an integral knob member 38 formed at the apex of bell-shaped fitting 34. The upper end of rod 370 is connected to one end of lever 37b, which is pivotally mounted in a yoke member 370 carried on an upper deck plate 40 ofthe diecasting apparatus. As will be apparent from the drawing, lever 37b may be moved upwardly to force fitting 34 downwardly against stud fitting 32 to assure good sealing contact between the fittings. Conversely, the lever may be moved downwardly to disengage rod 37a from fitting 34 when it is desired to disconnect the coupling 28 for cleaning purprovide a holddown means of the type described.

In a typical operation of the diecasting apparatus 10, a

general procedure for casting of the molten metal 14 in crucible 12 is as follows. A series of "test" shots are made to completely fill the passageway 26 in pumping and metering assembly 16 and passageway 30 in delivery line 18. Once the passageways are full ofmetal, electrical controls are employed to set the pump 22 on idle speed and to open the metering valve 24a. The speed of pump 22 is then increased to the point where the impeller 22a is continuously withdrawing metal from the crucible and filling the passageway 26 in the assembly l6 and passageway 30 in delivery line 18. After a preset period, valve 24a automatically closes to meter a given amount of metal into the delivery line 18 through passageway 26 and coupling 28. From delivery line 18 the premeasured amount of metal is injected into a die-assembly (not shown) to make the casting. Timer controls operating in conjunction with pump 22 and metering valve 24 open and close the die assembly according to an established sequence.

The importance of having a good liquidtight connection between the pumping and meter in assembly 16 in delivery line 18, as provided by the coupling 28, is readily apparent. For example, once metering value 2411 closes off passageway 26 during the metering sequence, the only way to hold the desired level of metal in delivery line 18, is to have a connection between passageways 26 and 30 which will not permit the metal to drain back into the crucible.

Although the coupling means of this invention has particular utility in a diecasting apparatus of the type used to cast light metals, such as alloys of magnesium, aluminum or zinc, it is not intended that the invention be limited to this precise concept. It is contemplated, for example, that the present coupling means may be used in any type of system requiring a leakproof, flexible, readily disconnectable coupling to join sections of conduit used to transport liquids from one point to another.

Iclaim:

1. In a pumping and metering assembly for transferring molten metal to a delivery line, an improved means for coupling the pumping and metering assembly to the delivery line, the coupling means comprising:

a stud fitting having a ball-shaped head portion and a lengthwise axial bore extending therethrough, the stud fitting being upstandingly affixed to the pumping and metering assembly such that the lower end of the fitting bore is in direct communication with the outlet end of a metalconducting passageway in said pumping and metering assembly;

a generally bell-shaped fitting having a central bore extending substantially lengthwise through the fitting, the bore including a lower bore section adapted to sealingly engage the head portion of the stud fitting and an upper bore section obliquely intersecting the lower bore section and being directly joined to the inlet end of a metal-conducting passageway in said delivery line.

2. The coupling means of claim 1 wherein the lower bore section of the bell fitting defines a frustoconical cavity having tapered sidewalls adapted to wedgingly engage the perimeter of the ball-shaped head portion ofthe stud fitting.

3. The coupling means of claim 1 wherein the upper bore section defines a cylindrical cavity, the lower end ofwhich intersects with an upper transverse wall of the lower bore section at an angle of about 45.

4. In a metal die casting apparatus including a pumping and metering assembly for transferring molten metal to a delivery line, an improved means for coupling the pumping and meterthe lower bore section and being directly joined to the ing assembly to the delivery line, the coupling means comprisinlet end of a metal conducting passageway in said ing: delivery line;

a stud fitting having a ball-shaped head portion and a holddown means adapted to engage the knob member of lengthwise axial bore extending therethrough, the stud 5 the bell-shaped fitting and to urge said fitting downwardly fitting being upstandingly affixed to the pumping and meagainst the stud fitting to thereby provide sealing contact tering assembly u h that the low d f h f i b between the lower bore section of the bell fitting and the is in direct communication with the outlet end of a metalhead Portion of the d fining conducting passageway in said pumping and m t i 5. The die-casting apparatus of claim 4 in which the holdm 10 down means is defined by an upstanding rod having a recess in a generally |l h fini having an integral knob the lower end thereof adapted to engage the knob member of member at the apex of the fitting, the fitting including a the fittingfmd the PP end of h being adapted for central bore extending Substantially lengthwise through engagement with a lever member carried on the diecasting apthe fining, the bore including a lower bore Section paratus and adapted for effecting up and down movement of adapted to sealingly engage the head portion of the stud the fitting and an upper bore section obliquely intersecting 

1. In a pumping and metering assembly for transferring molten metal to a delivery line, an improved means for coupling the pumping and metering assembly to the delivery line, the coupling means comprising: a stud fitting having a ball-shaped head portion and a lengthwise axial bore extending therethrough, the stud fitting being upstandingly affixed to the pumping and metering assembly such that the lower end of the fitting bore is in direct communication with the outlet end of a metal-conducting passageway in said pumping and metering assembly; a generally bell-shaped fitting having a central bore extending substantially lengthwise through the fitting, the bore including a lower bore section adapted to sealingly engage the head portion of the stud fitting and an upper bore section obliquely intersecting the lower bore section and being directly joined to the inlet end of a metal-conducting passageway in said delivery line.
 2. The coupling means of claim 1 wherein the lower bore section of the bell fitting defines a frustoconical cavity having tapered sidewalls adapted to wedgingly engage the perimeter of the ball-shaped head portion of the stud fitting.
 3. The coupling means of claim 1 wherein the upper bore section defines a cylindrical cavity, the lower end of which intersects with an upper transverse wall of the lower bore section at an angle of about 45*.
 4. In a metal die casting apparatus including a pumping and metering assembly for transferring molten metal to a delivery line, an improved means for coupling the pumping and metering assembly to the delivery line, the coupling means comprising: a stud fitting having a ball-shaped head portion and a lengthwise axial bore extending therethrough, the stud fitting being upstandingly affixed to the pumping and metering assembly such that the lower end of the fitting bore is in direct communication with the outlet end of a metal-conducting passageway in said pumping and metering assembly; a generally bell-shaped fitting having an integral knob member at the apex of the fitting, the fitting including a central bore extending substantially lengthwise through the fitting, the bore including a lower bore section adapted to sealingly engage the head portion of the stud fitting and an upper bore section obliquely intersecting the lower bore section and being directly joined to the inlet end of a metal conducting passageway in said delivery line; holddown means adapted to engage the knob member of the bell-shaped fitting and to urge said fitting downwardly against the stud fitting to thereby provide sealing contact between the lower bore section of the bell fitting and the head portion of the stud fitting.
 5. The die-casting apparatus of claim 4 in which the holddown means is defined by an upstanding rod having a recess in the lower end thereof adapted to engage the knob member of the bell fitting and the upper end of the rod being adapted for engagement with a lever member carried on the diecasting apparatus and adapted for effecting up and down movement of the rod. 